I Didn't Know That: Aiming Rockets

JONNY PHILLIPS:Since the invention of rockets by the Chinese 800 years ago, military men the world over have been keen to harness the destructive power of the black powder. But there was one big problem which dogged them for centuries: how on Earth do you get them to fly straight?

RICHARD AMBROSE: One early modification to improve accuracy was the addition of a long stick. And the length of the stick really does effect how straight a rocket flies.

JONNY PHILLIPS: First of all, we're gonna try this rocket which has no stick at all and we're gonna try and hit that target over there. Here goes.

RICHARD AMBROSE: Yep – here's it going.

NARRATOR: Despite numerous attempts there was just no way the boys could get a rocket without a stick anywhere near the target one hundred metres away. They just tumbled through the air and got diverted off course.

RICHARD AMBROSE: Half stick.

JONNY PHILLIPS: Go for it.

RICHARD AMBROSE: Right – I'm getting clear of that.

JONNY PHILLIPS: All right.

RICHARD AMBROSE: That's not so good.

JONNY:

Oh I dunno - I mean it weaved a bit, but its general direction was spot on.

NARRATOR: Doubling the length to 30 centimetres should make the flight straighter.

NARRATOR: To be honest, the real art of getting a rocket to fly straight and true is making it spin.

JONNY PHILLIPS: OK Rich.

RICHARD AMBROSE: Cheers, Jonny. Stand back now.

NARRATOR: The gyroscopic effect makes the flight much more stable.

RICHARD AMBROSE: Ooh, that's still warm. During the twentieth century the science of rocketry really took off and military rockets stopped being over grown fireworks and became weapons of mass destruction.

NARRATOR: The most famous of all is the V2. Its guidance system wasn't perfect but the speed it travelled at was astonishing. At a time when a Spitfire fighter plane flew at 600 kilometres an hour, the V2 could do 6000 kilometres an hour, carrying a ton of high explosives to targets hundreds of kilometres away. At the end of the second world war there was a race between the Russians and Americans to capture the German boffins who built the V2.

JONNY PHILLIPS (PTC):

These German scientists eventually made invaluable contributions to the space programmes of both nations and helped to develop some of the most extraordinary rockets the world has ever seen. Houston. Houston, we have a problem.

NARRATOR: On today's modern battlefields rocket weaponry is commonplace. But rockets can be used to save lives too. If your plane's going down you need to get out fast and the best way to do that is with a rocket powered ejector seat. The reason why ejector seats are needed is because of wind pressure. As this 1940s training film shows, even at relatively show speeds wind pressure makes it very difficult to jump clear of the aircraft. In an emergency, with the plane speeding towards the ground, it would be even harder. And at supersonic speeds it would be impossible. Which is why modern fighter pilots rely on rockets to make a sharp exit.